Ceramic heater

Abstract

The objective of the present invention is to provide a heater wherein it is easy to forcibly cool the remaining heat of a heating element, wherein it is easy to control the resistance value of the heating element, wherein the temperature of the periphery does not become lower than a set value and wherein no cracks are generated by rapid temperature rising and rapid temperature falling. The present invention provides a ceramic heater comprising a ceramic substrate and a resistance heating element formed on the surface of the ceramic substrate, wherein the outermost circumference of a resistance heating element- formed area is located within 35 mm from the side face of the ceramic substrate.

1 . A ceramic heater comprising a ceramic substrate and a resistance heating element formed on the surface thereof, 
 wherein the outermost circumference of a resistance heating element-formed area is located within 35 mm from the side face of said ceramic substrate.    
     
     
         2 . The ceramic heater according to  claim 1 , 
 wherein said ceramic substrate is in a disc shape.    
     
     
         3 . The ceramic heater according to  claim 1  or  2 , 
 wherein said ceramic substrate is a carbide ceramic or a nitride ceramic.  
 
     
     
         4 . The ceramic heater according to  claim 1  or  2 , 
 wherein the thickness of said ceramic substrate is 25 mm or less.  
 
     
     
         5 . The ceramic substrate according to  claim 1  or  2 , 
 wherein the diameter of said ceramic substrate exceeds 150 mm.